Solid ring cutters have been known for many years in the art of milling and, in particular, gear cutting. Wildhaber U.S. Pat. No. 2,129,077 discloses a solid ring cutter mounted to the nose of a cutter spindle. The solid ring cutter is stated to be very stiff due to the continuous ring and accurately concentric due to the fact that the teeth are ground in place.
It can be seen that producing the teeth of the ring cutter in place is advantageous since this approach eliminates the need to assemble a cutter by placing and positioning individual blades in a cutter head, such as illustrated by Blakesley U.S. Pat. No. 4,575,286, or mounting blades about the periphery of a cutter head, such as illustrated by Carlsen U.S. Pat. Nos. 2,994,943 et al. or Dammert et al. 3,138,996.
However, mounting a cutter ring on a spindle as disclosed by previously mentioned U.S. Pat. No. 2,129,077 or mounting a cutter ring on a cutter head as disclosed by McMullen U.S. Pat. Nos. 2,828,672 or McCray et al. 4,204,787 requires a precise fit of the cutter ring base and side mounting surfaces to the mounting surfaces of the spindle or head. Any dimensional changes of the cutter ring, such as diameter changes due to temperature variations, will result in the cutter ring and the surface to which it is to be mounted to lose the precise fit required for proper operation of the cutter. Proper operation being the ability of the cutter ring to rotate true about the axis of rotation of the spindle. A cutter ring produced at one temperature and then transported to another location having a different temperature will expand or contract accordingly. The diameter of the cutting ring will not be the same as when produced and will not precisely fit the intended mounting surface.
Producing the cutter ring and mounting surface under the same conditions does not solve the imprecise fit condition since usually the cutter ring is made from a cutting tool steel and the head to which it is to be mounted is made from a non-cutting tool steel. These materials most likely will not expand nor contract equally and therefore exposing the cutter ring and mounting surface to a temperature different than that at production will also ruin the precise fit of the cutter ring on the mounting surface.
It is an object of the present invention to provide a rotary ring cutter wherein the cutter ring will be concentric with the axis of rotation of the rotary cutter regardless of dimensional changes effected by exposure of the cutter ring to differing environmental conditions.
It is another object of the present invention to provide a rotary ring cutter which offers rapid assembly and disassembly as well as repeatable accurate placement of a cutter ring on the cutter head.